The efficient use of exhaust gas recirculation (EGR) is important to all modern internal combustion engines, including both gasoline and diesel engines. Efficient use of EGR generally supports the objectives of realizing high power output from these engines while also achieving high fuel efficiency and economy and achieving increasingly stringent engine emission requirements. The use of forced-induction apparatus, particularly including turbochargers and superchargers, in these engines is frequently employed to increase the engine intake mass airflow and the power output of the engine. In addition, superchargers include mechanical drive components, such as belts, gears, shafts or chains that are connected to the engine's crankshaft, and may present engine packaging challenges. Turbochargers are powered by exhaust gas, so the efficient use of EGR and forced-induction necessitates synergistic design of these systems.
It is desirable to have turbocharged or supercharged engines efficiently use the energy available in the exhaust system in order to improve overall engine efficiency and fuel economy. Further, as engines become more complex, packaging of various components can make design of the turbocharger or supercharger challenging. For example, as emissions regulations become more stringent, a closely coupled catalytic converter may be mounted directly to the turbocharger exhaust outlet. This may impact the positioning of EGR system components, such as exhaust gas supply and receiving ports. Accordingly, improved packaging of the turbocharger, air induction system, exhaust system and EGR system will enable the expanded use of turbochargers and EGR systems in a variety of applications, thereby leading to improved efficiency and performance.